Protective system for fluid cooled tubes



March 7, 1933. Y GEBHARD 1,900,013

PROTECTIVE SYSTEM FOR FLUID COOLED TUBES Filed Feb. 12, 1930 2Sheets-Sheet 1 ,INVENTOR. $044443 01. swgmw,

ATTORNEY March 7, .1933.

Filed Feb. 12, 1950 L. A. GEBHARD PROTECTIVE SYSTEM FOR FLUID COOLEDTUBES 2 Sheets-Sheet 2 3 p 4 T T v IN V EN TOR.

WM 61 425 aw By a ATTORNEY Patented Mar. 7, 1933 UNITED STAES PATENTOFFICE LOUIS A. GEBI-IARD, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNORTO WIRED RADIO, ING, OF NEW YORK, N. Y., A CORPORATION OF DELAWAREPROTECTIVE SYSTEMv FOR FLUID COOLED TUBES Application filed. February12, 19-30. Serial No. 427,985.

My invention relates broadly to high power electron tube systems, andmore particularly to a protective circuit for such systerns.

One of the objects of my invention is to provide an apparatus andcircuit arrangement for protecting high power tubes against destructiveefiects of high temperature during operation.

Another object of my invention is to provide a circuit arrangement andapparatus for cutting off the power circuits to a high power tube in theevent that excessive temperature conditions should arise during theoperation of the electron tube.

A further object of my invention is to provide a construction ofprotective device which is insertable within the fluid circulatingjacket of a high power tube structure for operation under conditions ofexcessive temperature for cutting off the power circuits to the highpower tube and thereby protecting the high power tube againstdestruction.

Other and further objects of'my invention reside in the construction ofprotective device which is insertable in the wall of the fluid coolingjacket of a high power tube structure for preventing injury to the highpower tube structure upon excessive rise in temperature as set forth inthe specification hereinafter following by reference to the accompanyingdrawings, in which:

Figure 1 is a fragmentary view of a high power tube mounted in a fluidcooling jacket and illustrating the temperature control mechanism withparts broken away and il lustrated in cross-section; Fig. 2 is acrosssectional view through the circuit controller on line 2-2 of Figure1; Fig. 3 is a crosssectional view through the thermostatic con- 'trolmeans on line 33 of Figure 1; and

Fig. 4 is a circuit diagram showing the arrangement of thecontact systemwhich controls the power supply to the high power tube.

Heretofore in the art various forms of protective systems have beenproposed for high power tubes. Such systems have generally depended uponthe temperature of the cooling fluid at a point adjacent the discooledinductance coil before reaching the control point which determines thecondition of the circuit for supplying power to the tube. I have foundthat this form of control is often too remote to protect a tube againstinjury as delays occur before the control will act. To avoid this delay,I have devised an arrangement where the operation of the control isdetermined immediately at the point where the temperature is importantand where destruction and injury to the tube may arise, that is,immediately adjacent the anode of the high power tube. I insert in onewall of the fluid cooling jacket, a member which transfers by conductiona portion of the heat existent immediately at the anode. A thermostaticelement is operated by the heat thus transferred to control a contactorsystem which opens and closes the power control circuit for shuttingdown the tube and preventing operation of the tube at excessivetemperatures.

The protective device is shown more fully in the drawings as comprisinga metallic tube 1 inserted in the wall 2 of the fluid jacket 3containing fluid cooled vacuum tube 4. The tube 1 has its inner endclosed off and projecting into the path of the cooling fluid which flowsas shown by the arrows in Fig. 1. The fluid passes upward over thesurface of the anode 5 and between it and the wall of the tube 6 untilit reaches the opening 7. From this point it passes through the openingbetween the wall'of tube 6 and the inner wall of the jacket 2 past thetube 1. The tube 1 is mounted as close to opening 7 as possible so thatthe heated fluid will reach it as soon as possible. On the tube 1 ismounted one end of bimetallic spiral strip 8. The other end of thespiral strip 8 is mounted on part 9 which is connected to insulatingshaft 10. Insulating shaft 10 is supported at one end in a bearing intube 1 as shown at 11 and is free to revolve. The other end of issupported in a bearing mounted on the frame of the radio transmitter asshown at 12. Shaft 10 is formed of insulation material of appropriatedescription for mechanically connecting the tube 1 while preventing anyelectrical connection therewith, as tube 1 is electrically connected tothe anode of tube 3 and it is essential to prevent short circuiting theframe of the radio transmitter. The electrical connection between tube 1and the fluid jacket is shown at 13. Tube 1 has a shoulder 14 and athreaded portion 15 on which a nut 16 may be screwed. Plate 17 is madeof heat insulating material such as mica to isolate tube 1 from the wall2 of the fluid jacket. This is to prevent conduction of the heattransmitted to tube 1 from the fluid being conducted away to the Wall 2.This permits the temperature to rise rapidly in tube 1 and in thebimetallic spiral S which is connected to the tube. Heat in sulatingmember 17 is made up in the form of a ring, the outer edge which ismounted in member 18 which is fastened to the wall 2 of the fluidjacket. A washer 19 and nut 20 provide a means for locking the member 1?in place. The heating of the bimetallic spiral 8 causes a turning of theshaft 10. Shaft 10 has mounted on it a cam 21 which actuates contacts22.

This is shown more clearly in Fig. 2. The contact 22a-is mounted on aninsulating arm 23 pivoted at 24. Contact 22b is mounted on a stationaryinsulating part 27. Contacts 22a and 22?) are held closed by means ofspring 40. Wire 28 affords a connection to contact 22a. An adjustingscrew 25 makes possible the setting of the particular point ofengagement of this screw with cam 21. A. screw 26 permits the adjustmentof the cam 21 with respect to the shaft 10. The shaft 10 is designedwith a minimum cross-section to prevent too rapid conduction of the heatfrom tube 1.

The bearing 11 in tube 1 may be eliminated and the bearing supplieddirectly from the wall 2. This arrangement eliminates all possible pathsof conduction of heat from tube 1 except through metallic spiral 8.

In Fig. 3, the method of attaching the thermo or bimetallic filament 8between the shaft 10 and the heat transfer element 1 is shown moreclearly. It will. be observed that expansion and contraction of thespiral 8 subjects shaft10 to a twisting force serving to operate theswitch contacts. The bimetallic member must operate against the ten-.sion of's rin 10 in openin the contacts 22.

ID D

To secure the required motion, a multiplicity of spirals may be employedfor the bimetallic member 8.

In Fig. 1, I have illustrated diagrammatically the contacts 226 and 22aconnected in the power supply circuit 41 in circuit with momentarycontact switches 29 and 30, and in circuit with relay windings 32 and 31such that both the cathode circuit through transformer 33 and the anodecircuit through switch 34 are opened when the temperature of the coolingfluid becomes excessive. I have illustrated the high power electrontube- 35 connected in a conventional power amplification circuit havingan input system 36 and an output system 37. The power supply circuit forthe anode is shown at 38. The cathode potential is supplied through 39.The biasing circuit for the grid system obtains its power from source42. To prevent excessive radiation from bimetallic spiral 8 and preventthe influence of air currents in the radio transmitter, a shield orcover may be placed over the bimetallic spiral.

The bimetallic control element of my invention is very sensitive in itsoperation in;

that the temperature immediately at the high power tube is thecontrolling factor for effecting operation of the power supply relaycircuits. The parts of the bimetallic element and switch mechanism maybe relatively small. The protection which is obtained may mean thedifference between sudden destruction and safety of a high power tube attimes when a prolonged shut-down of the transmitter might prove highlydisastrous.

While I have described my invention in a certain preferred embodiment, Idesire that it be understood that modifications may be made and that nolimitations upon my in vention are intended other than are imposed.-

by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A high power tube system including a high power electron tub-eincluding an electrode having an exposed surface, a jacket enclosingsaid electron tube and arranged for the circulation of a cooling fluidaround said electrode. a thermally conductive element extending throughsaid jacket, an an gularly shifta'ble shaft member journaled in saidthermally conductive element. a thermostatic member extending betweensaid thermally conductive element and said angularly movable shaft. aswitch controlled by said angularly movable shaft, said switch operatingto interrupt the power supply circuits to said electron tube underconditions of excessive temperature within the jacket surrounding saidelectron tube.

2. In a high power tube system, an electron tube having an electrode ofexposed surface area, a fluid cooling jacket surrounding said electrodefor the circulation of fluid around the exposed surface area of saidelectrode, a thermally conductive element extending through said jacketin the path of the cooling fluid therein, angularly movable shaft memberhaving a switch on one end thereof and being rotatably mounted in saidthermally conductive elementin the opposite end thereof, a thermostaticelement extending between saidthermally conductive element. and saidangularly movable shaft for angularly shifting the position of saidshaft under conditions of excessive temperature in said fluid coolingjacket and operating said switch to open the power circuits to saidelectron tube.

3. In a high power tube system, an-electron tube having an electrode ofexposed surface area, a fluid cooling jacket surrounding said electrodefor the circulation of cooling fluid over the exposed surface of saidelectrode, a thermally conductive element projecting through saidjacket, an angularly movable shaft member j ournaled in said thermallyconductive element, a thermostat connected at one end of said thermallyconductive element and connected at the other end to said a-ngularlymovable shaft member, and a switch controlled by said shaft for openingthe power circuits to said electron tub-e under conditions of excessivetemperature within said fluid cooling jacket.

4. In an electron tube apparatus, a fluid circulating jacket enclosingan electron tube, a circuit control device comprising a thermallyconductive member projecting into said fluid circulating jacket, anangularly movable shaft member, a switch controlled by one end of saidshaft member, the opposite end of said shaft member extending into asocket formed in said thermally conductive member, and a thermostaticelement connected between said thermally conductive mem her and saidangularly movable shaft member and adapted to rotatably shift saidangularly movable shaft member for opening or closing said switch.

5. In an electron tube apparatus, an electron tube having one of theelectrodes thereof enclosed in a fluid circulating jacket, a thermallyconductive member projecting into said jacket; said thermally conductivemember having a socket formed therein, an angularly movable shaft memberextending in axial alignment with said thermally conductive member withone end thereof projecting into the socket in said shaft member, aswitch controlled by the opposite end of said shaft member, and athermostatic element spirally disposed with respect to said thermallyconductive member and said angularly movable shaft member, one end ofsaid thermostatic element being connected to said thermally conductivemember and the opposite end of said thermostat element being connectedto said angularly movable shaft member for shifting said switch toeither of two positions.

6. In a circuit controlling device, a temperature varying chamber, ahollow tubular socket member projecting into said temperature varyingchamber, an angularly shiftable shaft member, one end of said shaftmember projecting into said hollow tubular socket member, a switchdevice controlled by the opposite end of said shaft member, and aspirally arranged thermostatic element having one end thereof connectedin heat conductive relation to said hollow tubular socket member and theother end thereof connected to said angularly shiftable shaft member andoperating to impart angular movement to said shaft member for actuatingsaid switch.

7. In a circuit controlling device, a heat conductive hollow tubularmember projecting into a temperature varying chamber, anangularly'movable shaft member, a switch 'device operated by one end ofsaid shaft member, the opposite end of said shaft ment ber projectinginto said hollow tubular member, and a pair of spirally arranged stripsof dissimilar metals connected at their inner ends with said hollowtubular member and connected at their outer extremities with saidangularly movable shaft member, whereby heat transferred to saiddissimilar metals serves to thermally expand or contract said membersfor imparting corresponding movement to said shaft member for actuatingsaid switch.

8. In a circuit controlling device, a heat conductive hollow tubularmember projecting into a temperature varying chamber, an angularlymovable shaft member of insulating material, a switch device operated byone end of said shaft member, the opposite end of said shaft memberprojecting into said hollow tubular member, and a. thermostatic elementhaving one end connected in a heat conductive relation with said hollowtubular member and the other end connected with said shaft member forcontrolling the operation or closing of said switch in a positionisolated from said thermostatic element.

9. In a circuit controlling device, a ther mally conductive memberextending into a temperature varying chamber, said member having asocket formed therein, a shaft member of insulating material having oneend extending into said socket, a switch member controlled by theopposite end of said shaft member, a thermostatic element connected inheat transfer relation to said thermally conductive element at one endand connected to said shaft member at the other end, and means foradjusting the position of operation of said switch according to aselected temperature transferred by said thermally conductive element.

LOUIS A. GEBHARD.

